APPLICATION OF GROUND-BASED GPS PRECIPITABLE WATER VAPOR TO MONITOR HEAVY RAINFALL EVENT OF 2011 IN BEIJING

Using the data of GPS continual operational reference system to retrieve the precipitable water vapor.According to the heavy rainfall from 24th to 26th July in 2011,the relationship between the variation characteristic of multi-stations' precipitable water vapor(PWV) and heavy rainfall was analyzed.And the relationship between the variation of precipitable water vapor and moisture transportation was also analyzed.By means of analysis of time series of GPS data from multi-stations,the paper obtains change characteristic of three phases of PWV during heavy rainfall period.Before the heavy rainfall period coming,PWV has a rapid rise.The length,extent and magnitude of the rapid rise reflect accumulation of water vapor,it has a better corresponding relationship with precipitation process during heavy rainfall period;and the process that the rapid rise of PWV reaches the peak has concomitant obvious precipitation,after entering high fluctuation phase,the precipitation holds on,in the course of PWV descends,the precipitation steps down,up to stop.In the phase,the fluctuation of time series of PWV and spatial distribution have a better corresponding relationship with short-term change of precipitation during heavy rainfall period;reposefully diminishing of change amplitude and average magnitude of PWV reflect that the heavy rainfall period is about to end.According to the comparison among the precipitable water vapor of five stations,the variation of GPS precipitable water vapor is corresponds to the moisture transport from the southwest to the northeast.